Vacuum-pump.



W. B. M. GRELGK. VACUUM PUMP. APPLICATION FILED AUG. 4, 1906.

Patented Sept 15,1908.

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UNITED STATES PATENT OFFICE.

WILLIAM P. M. GRELOK, OF ELGIN, ILLINOIS, ASSIGNOR TO ELGIN MILK ANDCREAM GOM- PANY, OF ELGIN, ILLINOIS, A CORPORATION OF ILLINOIS.

VACUUM-PUMP.

Specification of Letters Patent.

Patented Sept. 15, 1908.

To all whom it may concern:

Be it known that I, WILLIAM P. M. GRELOK, a citizen of the UnitedStates, residing at Elgin, in the county of Cook and State of Illinois,have invented a new and useful Improvement in Vacuum-Pumps, of which thefollowing is a specification.

My invention relates to mechanism for exhausting the air from Vacuumpans, vats and the like.

It is the common practice in evaporating milk, sap, syrup and otheraqueous fluids to do this in vacuo. The temperature at which the Wateris evaporated may thereby be much reduced and the rapidity by which itis taken of]? greatly increased. The more rapid and complete thereduction in the atmospheric pressure, the more speedy and economicalbecomes the process of condensation. But the machines which have beendesigned for this purpose do not make a complete vacuum at each strokeof the operative mechanism. A theoretically com plete vacuum isimpossible, but such mechanism usually has used a cylinder and pistonwith some form of D cut-off valve to control the tank and cylinderexhausts. The passages and chambers of such valves are of considerablesize and, together with other ele ments, embrace in comparison with theavailable cylinder capacity, not less than ten per cent. of the whole.This loss takes place and is repeated at every stroke of the piston andrepresents a great loss of efficiency in practical operation. In myinvention the capacity of the communicating portions outside thecylinders is practically reduced to nothing with a correspondingly greatincrease of efficiency and economy of practical results. Thesestatements also apply to condensation or compression apparatus, and myimproved machine is adapted for use as a compressor with similaradvantages of efiiciency and economy. I shall describe it as a vacuummachine, but it is to be understood that the description and claims areapplicable to it in either capacity.

The principles of my invention are illustrated in the drawings, inwhich:

Figures 1 and 2 respectively represent a plan view of and side elevationof one embodiment of my invention; Fig. 3 is an enlarged verticalsection of the cylinder on the line 3-3 of Fig. 1; Fig. 4 is an end viewof the same, with the outer casing removed; Fig. 5 is a detailed view ofa cylinder exhaust valve, and Fig. 6 is a vertical section of the sameon the line 66 of Fig. 5.

Further describing my invention with reference to the drawings, in whichlike characters of reference denote like parts throughout: 1 is anexhaust cylinder containing the piston head 2, which 'is operativelyconnected by the piston rod 3 to any suitable or practical drivingmechanism, by which reciprocating motion may be given. The cylinderbarrel 4 is flanged at 5 in the usual manner, by which cylinder headsmay be attached. The cylinder heads should preferably be extended beyondthe circle of the cylinder in rectangular form, and rectangular casings7, which may be of cast metal, are provided with openings 8 throughwhichthey may be secured to the cylinder heads by the bolts 9. An externalplate 10 is secured to the casing 7 by the tap bolts 11. The said casing7 should have a partition 12 by which the space Within the casing andbetween the cylinder head and the outer casing may be divided into twochambers 15 and 15, 16 and 16 at either end of the cylinder.

20 represents a pipe connecting with any tank or chamber which is to beexhausted and which by the branches 21 and 21 is connected to the tankexhaust chambers 15 and 15. A similar pipe 22 may be open to theexternal air and is connected by the branches 23 and 23 to the cylinderexhaust chambers 16 and 16. Ports 25 and 25 in the cylinder headcommunicate with the corresponding tank exhaust chambers, and cylinderports 26 and 26 communicate with the cylinder exhaust chambers. Withinthe said chambers are slide valves 27 and 27, 28 and 28 which should besuitably machined on their under faces, as well as on their upper andlower edges and adapted to move in suitable guides across the ports.When in operation the air pressures involved will normally keep theseslide valves in contact with the cylinder head, but to keep them in thisposition when not under pressure spring or similar guides 30 and 30, 31and 31 may be employed. The valves should be connected by suitable valvestems 33 and 33, 34 and 34: passing through glands 35 and 35, etc. Theseare attached to eccentrics 36, 36, 37

and 37 carried on the shafts 38, 39 parallel with the axis of theexhaust cylinder. These shafts may be connected up and driven in anyconvenient way. A practical means by which they may be actuated in fixedrelation to each other is shown in the drawings in which ll is a wheelto be connected in fixed relation to the source of power (not shown) bywhich the-piston rod 3 is actuated. A gear 42 is connected therewithwhich meshes with the pinion 43 on the shaft 44. On the other end ofsaid shaft is the bevel gear 45 meshing with the bevel gear 46, which issecured to the eccentric shaft 38. By similar means the eccentric shaft39 may be driven by means of the bevel gears 47 and 48. It will be seenthat by giving any desired throw to the eccentrics and by giving themthe proper relation to each other, which may be done by the mechanism.shown, or any other similar one whichwill readily occur to one skilledin the art, the cut-off valves may be actuated to such distances and insuch relation to each other as may be desired.

The lower slide valves 28 and 28 which control the cylinder exhaustshould have perforations corresponding to the ports which they controland an auxiliary valve of some form should be provided to control thesaid opening. This may be of the hinged type and comprise a sheet ofspring metal 40.

The operation of my machine is as follows: Assuming the piston head tobe at the position shown in Fig. 3, the ports 25 and 26 should beuncovered by the slide valves while 25 and 26 are closed. The pistonhead being moved to the other end of the cylinder, air from the exhausttank will flow through the pipe 20, the branch 21, the tank exhaustchamber 15 and the port 25 to fill the bore of the cylinder, the normalair behind the piston head being expelled from the bore through the port26 and its corresponding passages. pleted its travel, being in as closecontact with the head 6 as is safely possible, the motion is reversedand the previously opened slide valves closed, while the valves 27 and28 are opened. The movement of the piston head to its first positionwill exhaust air through the pi e 20, the branch 21, the tank exhaustcham er l5 and the port 25 to fill the cylinder in the rear of thepiston, while the air in front of the piston which, at its previousmovement had been drawn there from' the exhaust tank, will be expelledthrough the port 26. Such expulsion, however, will not be immediate. Theair in front of the piston having been drawn from the tank to beexhausted under less than atmospheric pressure the slide valve 28 havingbeen moved, as it should be by its corresponding eccentric, until theopening therein registers When the piston head has com-- with the port26, the normal movement of air would be inward to restore theequilibrium, but the valve 45 on the slide valve 28 prevents ingress ofair and the initial movement of the iston will be aided bythe exhaustair in 'ront of it until the equilibrium is restored. At this point theplate valve 40 will release and the inclosed air will flow freelythrough the port into the cylinder exhaust chamber and thence to theopen air. It will be seen that a great economy of power is obtained bythis action, constantly increasing as the degree of exhaustion in thetank progresses. With the exhaustion of each stroke the vacuum isincreased and on the return this vacuum will act for a longer period toaid the operation of the piston and until the equilibrium with theexternal air pressure is restored. It will be seen that as the vacuumbecomes more perfect, this directly aids the operation of the piston andthe amount of power required during the whole process is increased butlittle if any. It will further be seen that the amount of dead space inthe cut-off mechanism is limited to the actual area of the ports'and thethickness of cylinder heads in which they are placed. This is so slightas to be of very little importance. The entire contents of the cylinderare exhausted at each stroke, less only the capacity of the ports andthe necessary clearance of the cylinder head.

' To prevent heating of the apparatus in use, it is desirable tosurround the cylinder with a water jacket. The cylinder heads beingrectangular, I prefer to have the outer walls 50 of the Water jacketfollow the interior edges of the cylinder heads, thus forming arectangular casing around the circular cylinder and providing therebygreater space for the water. The water may be supplied. to the waterjacket through the pipe 52 and withdrawn therefrom through the opening53.

I claim:

1. In a vacuum pump, a cylinder, a piston moving therein, a casingsecured to the cylinder head, a transversely-extending partition in saidcasing dividing the same into a plurality of chambers out ofcommunication one with the other, ports in the cylinder headestablishing communication between said chambers and the cylinder, atransversely-slidable cylinder exhaust valve in each chamber of saidcasing to control said ports, and an auxiliary valve carried by eachexhaust valve.

2. In a vacuum pump, a cylinder, a piston moving therein, a tank exhaustchamber external to the cylinder head, .a port between the said chamberand the cylinder, a valve to control the port, an exhaust chamberexternal to the head and separated from the tank exhaust chamber, a portbetween the said exhaust chamber and the cylinder, an exhaust valve tocontrol said port, and

means in connection with said exhaust valve for holding the exhaustuntil equilibrium with the outside pressure is obtained. 3. In a vacuumpump, a cylinder, a piston moving therein, a tank exhaust chamberexternal to the cylinder head, a port between the said chamber and thecylinder, a sliding valve to control the port, an exhaust chamberexternal to the head and separated from the tank exhaust chamber, a portbetween the said exhaust chamber and the cylinder, a sliding valve tocontrol the same, and an auxiliary valve carried by said sliding valve.4. In a vacuum pump, a cylinder, a piston acting therein, tank exhaustchambers at opposite ends of the cylinder external thereto, portsconnecting said chambers and the cylinder, valves to control said ports,cylinder exhaust chambers at opposite ends of the cylinder externalthereto, ports connecting the last named chambers to the cylinder, andsliding valves to control said orts, the tank chamber at each end of thecy inder being separated from the cylinder exhaust chamber at the sameend, and means in connection with said sliding-valves for holding theexhaust until equilibrium with the outside pressure is obtained.

5. In a device of the character described, a cylinder exhaust valve adated normally to control its port, and an auxi iary valve thereon adaptedto prevent ingress of external air after exhaustion until the externalpressure and the pressure in the exhaust end of the cylinder are inequilibrium.

6. In a vacuum pump having inlet and exhaust valves connected witheither end of the cylinder, and means for actuating the valves inrelation to the piston movement, means connected with the exhaust valveior holding the exhaust until, on the return of the piston, equilibriumwith the outside pressure is obtained.

In Witness whereof I have hereunto set my hand, this 31st day of July A.D. 1906, in the presence of two subscribing witnesses.

WILLIAM P. M. GRELCK.

WVitnesses:

O. K. CHAMBERLAIN, A. S. PHILLIPS.

